So if they were identical - what stopped it flying in 1905 Simplex ?
It's complete lack of existence, of course.
Don't you see the scheme? They completely designed the 1908 Flyer III in the four weeks between the U.S. government's 23 December 1907 request for proposal, and the submission of their 28 January 1908 letter that included one of their alleged 1905 photos. However, it was really just built during that short period of time in order to take that and all of the other "1905" photos. By labeling them all "1905," it looked like they'd had been in possession of the design for a long time which gave them a leg up on all the other successful bidders. Lucky thing it flew so well since they just whipped it together at the last moment. It's so simple.